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This paper presents the design and implementation of a CMOS transformer combiner that can be reconfigured to have similar efficiencies at widely separated frequency bands. Conventional transformer combiners employ a fixed tuning capacitance in the secondary network to optimize the efficiency for single frequency standard. In this work, we present a modified transformer combiner where digitally-switchable...
This paper presents the design and characterization of a miniaturized tunable bandpass filter utilizing high-Q ceramic coaxial resonators and commercially available RF-MEMS tunable digital capacitors. A proof-of-concept 2-pole tunable filter occupying only 10 × 10 mm2 is demonstrated with a frequency tuning range of 800–1100 MHz and bandwidth tuning range of 6–13%.
A compact CMOS voltage-controlled relaxation oscillator circuit is presented in this paper. The frequency control is fulfilled by using a single MOSFET to control the charging and discharging currents of a timing capacitor. This paper investigates and demonstrates the proposed control mechanism. The proposed VCO was fabricated using 0.18 μm CMOS technology and the fabricated VCO has a compact core...
This paper presents a third-order digital tunable bandpass filter based on digitally tunable capacitor loaded open ring resonator. Magnetic dominated mixed coupling is utilized to make the coupling coefficient meet the requirement of stable bandwidth response. Electric source-load coupling is designed to generate a transmission zero for improving the frequency selectivity. This filter is designed,...
An LC-tank quadrature voltage-controlled oscillator (QVCO) with an octave overall tuning range is designed and fabricated in AMS 0.35µm 2P/4M RF CMOS. The VCO utilizes an nMOS-based, cross-coupled, programmable-in-size-and-current active core for dual Gm-mode operation to overcome a tradeoff between the VCO minimum frequency limited by the startup gain of its active core and the VCO maximum frequency...
An exponentially-scaling C-2C switched-capacitor ladder is proposed for mm-Wave DCOs to achieve high frequency resolution with small chip area. The 65nm-CMOS DCO prototype measures frequency resolution of 4Hz over a frequency range from 54.79 to 63.16GHz with phase noise of −90.7∼−94.1dBc/Hz at 1MHz frequency offset while consuming 18mW, corresponding to FOMT from −176.6 to −180 dBc/Hz. The DCO occupies...
Wireless charging is a safe and clean technique of contactless charging over a wide range of power levels for portable electronic products. Although the market for wireless charging in Watts to tens of Watts is growing rapidly, the performance of such wireless charging products is still inferior when compared to those utilizing traditional charging, especially when the resonant frequencies are not...
This paper presents a digitally controlled oscillator (DCO) in inductor-capacitor (LC) topology with dual -band and fine frequency tuning steps. Using special Fibonacci sequence method and additional capacitor in the capacitor bank, this DCO operates two differential frequency bands and achieves finer tuning range than that of a conventional binary sequence DCO. The proposed circuit is implemented...
This paper demonstrates a fully integrated power amplifier for long term evolution (LTE) applications. The power amplifier is adopting a tuning capacitor in parallel with the choke inductor, which reduces the DC power consumption of the inductor and decreases the chip size. The total power added efficiency (PAE) is enhanced as a result. The proposed power amplifier is manufactured using a 0.25 μm...
Frequency tuning of aluminum nitride (AlN) micromechanical resonators has been demonstrated by reactance manipulation via termination with variable capacitors. Shunting one electrode with a variable capacitor in a 13 MHz fourth overtone length-extensional mode resonator effected resonator stiffening to yield a ∼600 ppm frequency shift. Tunability could be further increased by dedicating two electrodes...
This paper proposes a reduced-size and tunable 3dB branch-line hybrid. The proposed hybrid consists of short transmission lines with equal characteristic impedance and shunt lumped tuning capacitors. The authors fabricated the proposed hybrid on PTFE substrates at 2GHz. In the measurements, while tuning capacitance changes from 1.3pF to 2.7pF, center frequency shifted 1.8GHz to 2.4GHz, with −19.5dB...
A wideband Colpitts VCO using an analog tunable phase shifter as the frequency tuning component is presented. The tunable phase shifter is used as the resonator in a common collector Colpitts oscillator. An inductor is added in series with one of the feedback capacitors to avoid oscillation at higher order resonances of the phase shifter. The proposed VCO has a measured continuous frequency tuning...
This paper reports a Digitally Controlled Oscillator (DCO) with 20kHz frequency resolution. This is the first DCO implementing capacitor delta tuning and Dynamic Element Matching (DEM) to suppress process variations and mismatches between small capacitor deltas. The DCO is fabricated in 0.13μm CMOS IBM technology. The proposed DEM technique reduced the process variations and mismatches from 95% to...
A digital PLL, realized in 45nm SOI CMOS, features a dual LC-tank DCO with nested inductors, achieving an octave of tuning range and area of 0.111 mm2. Digital control of coupled LC-tanks creates new capabilities, enabling a 10% increase in tuning range and a 28 times reduction of DCO gain. The rms jitter, integrated from fc/1667 to fc/2, is 362 fs at 12 GHz and 274 fs at 6 GHz.
An integrated digitally-controlled crystal oscillator (DCXO) is presented that generates both 38.4 MHz and also a 32.768 kHz real time clock (RTC) from a single 38.4 MHz crystal. The DCXO can startup independently and transition seamlessly in and out of software control. The tuning range is 280 ppm with 2 ppb/step and guaranteed monotonicity. The phase noise is -135 dBc/Hz at 1kHz offset and -146...
We proposed a method to realize the fine frequency-tuning step using tiny capacitors instead of MIM capacitors for a digitally controlled oscillator (DCO). The tiny capacitors are realized by the coplanar transmission lines in a 6 metal layers (M6) foundry of 0.18 um CMOS technology. These transmission line based capacitors are designed by using electro-magnetic field simulator, and co-designed by...
This paper presents a novel wideband voltage-controlled oscillator (VCO) and a tunable power amplifier (PA) for multi-band transceivers. The proposed oscillator has a core VCO and a tuning-range extension circuit, which consists of an injection-locked frequency divider (ILFD), and flip flop dividers. The 2-stage differential ILFD can generate quadrature outputs, and it realizes 2, 3, 4, and 6 of divide...
This paper reports an LC-based digitally controlled oscillator (DCO) in 65 nm CMOS, key component in a digital phase locked loop, with an enhanced frequency resolution and extended tuning range. It has a center frequency of 5.8 GHz and a tuning range of 1800 MHz. The finest frequency step is about 20 kHz. The oscillator exhibits a phase noise of -100 dBc/Hz at 100 kHz frequency offset from 4.9 GHz...
The design and characterization of a CMOS-MEMS variable capacitor is presented. Measured results demonstrate a tuning ratio of 6.9:1, a quality factor of 28 at 3 GHz, and a self-resonant frequency of 11 GHz, with sub-50 fF parasitic capacitance. Simulations of two frequency-reconfigurable circuits, a low-noise amplifier and a power amplifier, show the importance of low parasitic capacitance for practical...
This paper deals with the design problems associated to the implementation of low power wide tuning band low phase noise LC VCOs in low cost Si-integrated technologies. For that, a VCO was developed using a low cost 0.35 mum 2-poly 4-metal standard CMOS technology. The VCO uses a radio frequency switched varactor array (RFSVA) in the tank circuit in order to decrease the influence of the varactor...
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